Method of controlling viscosity of hydrocarbon polymers



June 1, 1948. w. E. ELWELL ETAL -IE'I'I'IOD OP CONTROLLING VISCOSITY OFHYDHOCARBON POLYIEBS Filed April 2, 1946 Q a 2 w 3 .2 2 n o R v 3 $66RES 55:3: m M u m E A w m 4 7 A m Q 4 9 0 g 2: f... 4 329.4 352 i owuumsi m 3336 mo 38 5; 953%: a M w Hw 83 RI hard L Meier Patented June 1,1948 METHOD O1" CONTROLLING VISCOSITY F HYDROOABBONIOLMBS ApplicationApril 2, 1948, semi No. 659,024

14 Claims. (Cl. 280-689) This invention relates to a method ofcontrolling the viscosity of the polymers obtained by polymerizingunsaturated hydrocarbons with boron fluoride catalyst.

This method is particularly applicable to the polymerization ofmono-oleflns with boron fluoride catalyst; but it maylikewise be appliedto the copolymerization of said mono-oleiins with dioleiins or withcertain other unsaturated hydrocarbons, e. g., styrene.

In our copending application entitled "Process of activatingPolymerization of hydrocarbons and filed on the same date as the presentapplication, it has been disclosed that the polymerization ofmono-oleflns as well as the copolymerization of said mono-oleflns anddioleflns with boron fluoride catalyst may be substantially enhanced bythe presence of small amounts of sulfur dioidde. At the same time, ithas been pointed out that the use of such sulfur dioxide activatorresults in improved yields of polymeric products having a somewhat lowerviscosity than the products obtained in the absence of the sulfurdioxide activator.

We have discovered that, by increasing the concentration of sulfurdioxide above the range of amounts required to activate thepolymerization in the presence of boron fluoride up to 50% by volume (oreven more) of the oleflns present, it is possible to regulate theviscosity and, consequently, the molecular weight of the polymericproduct. With higher concentration of sulfur dioxide, the viscosity ofthe polymer decreases. and conversely, with lower concentrations ofsulfur dioxide, the viscosity of the polymer increases.

Briefly stated, our invention consists in a method of manufacturinghydrocarbon polymers of a specified viscosity by correspondingly varyingthe proportions of sulfur dioxide present in the polymerization or thecopolymerization of unsaturated hydrocarbon with boron fluoridecatalyst.

This application of sulfur dioxide to regulate the viscosity, andconsequently the molecular weight, of hydrocarbon polymers is totallyunexpected and unknown in the art. We believe that the polymerizationreaction of this invention occurs in three stages: (1) activation of theolefln bond by boron fluoride in the presence of sulfur dioxide toinitiate the polymerization reaction; (2) chain growth by reaction ofthe activated olefin molecule with other olefin molecules at rapid ratesto form polymer molecules; (3)

weight range by a little understood chain-transfer action of sulfurdioxide.

It will be noted that in small amounts (less than 1% by volume of themonomers) the action of sulfur dioxide is catalytic in that it activatesthe boron fluoride catalyst and increases the yield of polymer, whereasin concentrations of from 1% to by volume the chain-transfer propertiesof sulfur dioxide become foremost. This chain-growth termination in thefinal polymerization step results in the shortening of the molecularchain. and, consequently, in a lower molecular weight and a lowerviscosity of the polymeric product.

As may be seen from the appended graph in which the viscosity of thepolymer is plotted as a function of the amount of sulfur dioxideemployed (in per cent by volume), the proportion of sulfur dioxiderequired in each particular case is governed by the viscosity, andconsequently by the molecular weight of the polymer or the copolymer tobe obtained.

An additional advantage of the process of the present invention consistsin producing hydrocarbon polymers of a controlled viscosity in ahomogeneous-phase polymerization with boron fluoride catalyst, byemploying certain concentrations of the sulfur dioxide "molecular-chainterminator" which corresponds to the desired value of viscosity. Sincethe polymeric product is thus manufactured to specification grade as awhole, it becomes unnecessary to take distillation cuts from a polymerof broad molecular weight distribution, as is a common practice in themanufacture of viscous polymer oils.

In the practice of the present invention the amount of sulfur dioxide"molecular-chain terminator" should be not less than about 1% by volumeof the monomers present and preferably less than that amount as wouldcause the formation oi. two phases. In general. maximumviscosity-resulating effects are obtained with amounts of sulfur dioxidefrom about 1% to about 5% by volume of the monomers. However, additionalreduction in viscosity of the polymeric product is secured with sulfurdioxide in greater amounts. e. g., up to 50% and even more by volume.The exact proportion of sulfur dioxide permissible without formation oftwo phases depends in each particular case on the monomer beingpolymerized, the temperature of reaction and the amount of diluent ifany. For most systems up to 50% by volume is permissible.

The reaction temperature is an important varitermination of chain growthin ag-iven molecular is able of our process. In general. temperatureshigher than 0. up to 100' C. have a tendency to obscure thechain-terminating eflect of sulfur dioxide, since such highertemperatures also tend to produce polymers of lower viscosity. whencarried out at atmospheric pressures, the process is operative attemperatures of not lower than about 100 C. and not higher than 10 C.The upper limit of temperature may be raised correspondingly by usinghigher pressures. If so desired, inert diluents, preferably inertaliphatic hydrocarbons, e. g., butane, may be used with the monomers tobe polymerized.

The invention can be best understood from the following description orthe tests, the corresponding data in the tables, and the appended graph.

The reaction is carried out in a Pyrex-glass cylinder provided with aDry Iceacetone condenser. The monomers are fed into the cylinder throughan inlet near its top. Sulfur dioxide is condensed separately and pouredinto the reaction mixture through the vent of the condenser. Thereafter,the mixture is blown with boron fluoride at rates and times as specifiedin copolymerization o! propylene and styrene in Table 4.

It is seen irorn the above data that polymeric products of mono-oleflnsand dioleflns of a desired viscosity grade and molecular weight may bemanufactured by varying the eii'ective concentration of sulfur dioxidein accordance with the method oi the invention. Special oils andlubricants with properties that cannot be duplicated by the materialsproduced by petroleum refining methods can now be obtained by our newmethod employing liquid sulfur dioxide ior regulating the viscosity ofthe polymeric product. Likewise, copolymers of mono-olefins anddiolefins suitable for use as synthetic drying oils, for instanceeopolymers of propylene and butadiene, and valuable chemicalintermediates, such as copolymers of oleflns and styrene. may beprepared to suit the particular requirements or each case.

It is to be understood, of course, that the conditions and amountsdisclosed in the specific examples herein do not in any way limit thescope and the spirit of the present invention, and although the examplesdisclose only the polymerthe tables, ization oi lorwer oleflns, such aspropylene and Teen 1 Polymerization of propylene .1 m. r Butane Rate ofBF; Time Via. in t V Monomer SO11" Yield in lost I\0. diluent passe v.in B. B. U. at

m in c. e. c. cJNffn. Min. Per cent 210 F.

TABLE 2 Polymerization of isobutulene Butane Rate oi BF| Time Via. in vMonomer S0: in Yield in Post NO. diluent passage, in S. B. U. at

in in c. c. c. cJMln. Min. Per Gem 210 F.

5 250 200 0 50 35 91.8 1%,36. ii 250 200 2 50 35 70. 0 5, 827 7 250 20010 w 36 58- 5 102. 9

Tnnu: 3

Copolymerization of propylene and butadiene lluta- 1 Butane Amt oi TimeVis in Test No. pr-opyklne diene in diluent BFzused in 8.5. U.at

m c. c. in c. c. in liters Min. 210 F.

S 20D 50 200 0 12 150 l0,i]ill ii 200 50 200 10 17 180 226. l in 200 50200 50 11 57. o

Butylenes may also be copolymerized with butadiene under the conditionsindicated for the copolymerization of propylene and butadiene in Table3.

isobutylene, in its broader aspects the invention would embrace thepolymerization of higher olefins, as for instance pentenes, isoprene,etc.

We claim:

Team: 4

Copoiymerization of propylene and styrene l Petroleum Rate oi BF: TimeVis. in Propylene Styrene SO: in Yield in 'l est No. ether diluentpassage in 8. B. U. at

c in e. c. c. cJMin. Min. 210

11.. ion so 300 0 so 1.2 m i2 H mu :m 300 2 so no 53 104 1:; mu so am soso no ass 73.:

Likewise, butylene may be copolymerized with styrene under theconditions indicated for the 1. In a process of polymerizing normalmonooleilns in the presence of boron fluoride catalyst,

the step or controlling the viscosity of the polymer by incorporation ofsulfur dioxide in amounts of from not less than about 1% to about 50% byvolume of the mono-olefins.

2. A process as defined in claim 1 wherein the proportion of sulfurdioxide is from about 1% to about 5% by volume of the mono-olefins.

3. A process as defined in claim 1 wherein the normal mono-olefinscomprise propylene.

4. A process as defined in claim 1 wherein the mono-olefins comprisepropylene and the amount of sulfur dioxide is from about 1% to about 5%by volume of the normal olefins.

5. A process as defined in claim 1 wherein the normal mono-olefinscomprise a butylene.

6. In a process of copolymerlzing mono-olefins and diolefins in thepresence of boron fiuoride catalyst, the step of controlling theviscosity oi the copolymer by incorporation of sulfur dioxide in anamount oi from not less than about 1% to about 50% by volume or theolefin mixture.

'7. A process as defined in claim 6 wherein the amount of sulfur dioxideis from about 1% to about 5% by volume 01' the olefin mixture.

8. A process as defined in claim 6 wherein the mono-olefin comprisespropylene and the dlolefin is butadiene.

9. A process as defined in claim 6 wherein the mono-olefin comprises abutylene and the diolefln is butadiene.

10. In a process of copolymerizing mono-olefins with styrene in thepresence or boron fluoride catalyst, the step or controlling theviscosity of the copolymer by incorporation of sulfur dioxide in anamount or from not less than about 1% to about by volume of the olefinmixture.

11. A process as defined in claim 10 wherein the amount of sulfurdioxide is from 1% to 5% by volume of the olefin mixture.

12. A process as defined in claim 10 wherein the mono-olefin comprisespropylene.

13. A process which comprises polymerizing a normal mono-olefin withanother olefin miscible therewith, said process comprising catalyzingsaid polymerization with boron fluoride and controlling the viscosity ofthe polymer by incorporation of sulfur dioxide in an amount of from notless than about 1% to about 50% by volume of the mixed olefins.

14. A process as defined in claim 13 wherein the amount of sulfurdioxide is from 1% to 5% by volume of the mixed olefins.

E. ELWELL. RICHARD L. MEIER.

REFERENCES CITED The following references are of record in theCertificate of Correction Patent No. 2,442,644.

file of this patent:

UNITED STATES PATENTS Number Name Date 2,142,980 Huiiser et a1 Jan. 3,1939 2,220,307 Whiteley et al Nov. 5, 1940 2,229,661 Mann Jan. 28, 19412,274,749 Smyers Mar, 3, 1942 2,296,399 Otto et al. Sept. 22, 1942 June1, 1948.

I WILLIAM E. ELWELL ET AL. It is harsh certified that errors appear inthe printed specification of the above numbere patent requiringcorrection as follows: Column 3, line 18, for

"Dry Iceacetone readDry Ice acetone 5 Table 2, last column thereof, for103 36. read 108,867; same column 3, next to last line, for the word"butylene" read buty cues and that the said Letters Patent should beread with these corrections therein that the same may conform to therecord of the ease in the Patent Oflice.

Signed and sealed this 17th day of August, A. D. 1948.

THOMAS F. MURPHY,

Assistant Oommiuioner of Patents.

the step or controlling the viscosity of the polymer by incorporation ofsulfur dioxide in amounts of from not less than about 1% to about 50% byvolume of the mono-olefins.

2. A process as defined in claim 1 wherein the proportion of sulfurdioxide is from about 1% to about 5% by volume of the mono-olefins.

3. A process as defined in claim 1 wherein the normal mono-olefinscomprise propylene.

4. A process as defined in claim 1 wherein the mono-olefins comprisepropylene and the amount of sulfur dioxide is from about 1% to about 5%by volume of the normal olefins.

5. A process as defined in claim 1 wherein the normal mono-olefinscomprise a butylene.

6. In a process of copolymerlzing mono-olefins and diolefins in thepresence of boron fiuoride catalyst, the step of controlling theviscosity oi the copolymer by incorporation of sulfur dioxide in anamount oi from not less than about 1% to about 50% by volume or theolefin mixture.

'7. A process as defined in claim 6 wherein the amount of sulfur dioxideis from about 1% to about 5% by volume 01' the olefin mixture.

8. A process as defined in claim 6 wherein the mono-olefin comprisespropylene and the dlolefin is butadiene.

9. A process as defined in claim 6 wherein the mono-olefin comprises abutylene and the diolefln is butadiene.

10. In a process of copolymerizing mono-olefins with styrene in thepresence or boron fluoride catalyst, the step or controlling theviscosity of the copolymer by incorporation of sulfur dioxide in anamount or from not less than about 1% to about by volume of the olefinmixture.

11. A process as defined in claim 10 wherein the amount of sulfurdioxide is from 1% to 5% by volume of the olefin mixture.

12. A process as defined in claim 10 wherein the mono-olefin comprisespropylene.

13. A process which comprises polymerizing a normal mono-olefin withanother olefin miscible therewith, said process comprising catalyzingsaid polymerization with boron fluoride and controlling the viscosity ofthe polymer by incorporation of sulfur dioxide in an amount of from notless than about 1% to about 50% by volume of the mixed olefins.

14. A process as defined in claim 13 wherein the amount of sulfurdioxide is from 1% to 5% by volume of the mixed olefins.

E. ELWELL. RICHARD L. MEIER.

REFERENCES CITED The following references are of record in theCertificate of Correction Patent No. 2,442,644.

file of this patent:

UNITED STATES PATENTS Number Name Date 2,142,980 Huiiser et a1 Jan. 3,1939 2,220,307 Whiteley et al Nov. 5, 1940 2,229,661 Mann Jan. 28, 19412,274,749 Smyers Mar, 3, 1942 2,296,399 Otto et al. Sept. 22, 1942 June1, 1948.

I WILLIAM E. ELWELL ET AL. It is harsh certified that errors appear inthe printed specification of the above numbere patent requiringcorrection as follows: Column 3, line 18, for

"Dry Iceacetone readDry Ice acetone 5 Table 2, last column thereof, for103 36. read 108,867; same column 3, next to last line, for the word"butylene" read buty cues and that the said Letters Patent should beread with these corrections therein that the same may conform to therecord of the ease in the Patent Oflice.

Signed and sealed this 17th day of August, A. D. 1948.

THOMAS F. MURPHY,

Assistant Oommiuioner of Patents.

